1. Technical Field
The present invention relates to a method of fabricating a semiconductor device provided with two or more types of light receiving element.
2. Related Art
Conventionally, semiconductor devices provided with light receiving elements, for example illumination sensors, image sensors, or the like, are configured, for example, with two or more types of photodiode (light receiving element) formed in a silicon substrate.
For example, for an SOI substrate having a semiconductor layer formed on a semiconductor substrate with an insulating layer interposed therebetween, a method is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2006-24787 of removing the insulating layer and the semiconductor layer to expose a portion of the semiconductor substrate, forming a well in the exposed semiconductor substrate for forming a photodiode, and then forming a transistor in the semiconductor layer.
Also, in JP-A No. 2006-245246, there is a proposal to configure two or more types of photodiode such that they each have a different junction depth. In this proposal, sensitivity is imparted to light of comparatively shorter wavelengths as the junction depth gets shallower, and sensitivity is imparted to light of shorter comparative wavelengths when the junction is formed deeper. By detecting the photoelectric current from such photodiodes having sensitivity to different wavelengths, and by computation with a computation circuit, a photodiode is formed that suppresses sensitivity to the infrared wavelength region.
However, an extremely complicated structure arises when two or more types of photodiode (light receiving element) are formed in a silicon substrate, and there is a greater number of fabrication processes.